Process for removing nitrogen from petroleum hydrocarbons with an ester of a metaboric acid



Dec. 1958 F. J. DYKSTRA 1 2,862,879 PROCESS FOR REMOVING NITROGEN FROM PETROLEUM HYDROCARBONS WITH AN ESTER OF A METABORIC ACID Filed May 3, 1956 2 Sheets-Sheet 1 FIGURE LIGHT DISTILLATES /3 CRACKER ,0 N CHARGE STOCKS m CRUDE 2 STEAM STORAGE DISTILLATION REDUCED CRUDE FIGURE 2 V LIGHT- DISTILLATES A I CRACKER 23 2/ CHARGE STOCK STEAM 30 DISTILLATION 3/ CRUDE REDUCED CRUDE 'FRED J. DYKSTRA, INVENTOR.

WWW

Dec. 2, 1958 F. J. DYKSTRA 2,862,879 PRocEss FOR REMOVING NITROGEN FROM PETROLEUM HYDROCARBONS WITH AN EsTER OF A METABORIC ACID Flled May 3, 1956 2 Sheets-Sheet 2 FIGURE 3 eA4s2 OIL NON-VISCOUS 4/ NEUTRAL 43 7 62 g II p j CLAY g FILTRATION I: 5

52 3 50 ADDITIVES 5 58 60 5 49 53 6/ 59 I 56 MOTOR REDUCED CRUDE STEAM 48 54 CLAY on.

FROM PRIMARY REFINED 55 FILTRATION 5 BLENDING DISTILLATION STOCK FRED J. DYKSTRA, INVENTOR.

United States @PatentO Fred J. Dykstra, Detroit, Mich., assignor to Ethyl Corporation, New York, N. Y., a corporation of Delaware Application May 3, 1956, Serial No. 582,627

Claims. (Cl. 208254) This invention relates to a process for purifying heavy hydrocarbons and, more particularly, to a process for reacting heavy hydrocarbons with a reagent capable of improving the characteristics of the hydrocarbon with regard to subsequent refinery processes and the quality of the finished products derived therefrom. Further, this invention relates to the novel composition resulting from such reactions.

In the refining of petroleum and fractions thereof, the presence of nitrogen compounds is particularly undesirable. Nitrogen compounds, when present in hydrocarbon oils used as cracker charge stocks, are objectionable since these compounds destroy the activity of the hydrocarbon conversion catalyst with which the oil is brought into contact during various processing operations. Thus, in catalytic cracking of a hydrocarbon oil containing an appreciable amount of nitrogen compounds, the catalyst prematurely loses activity due to the poisoning efiects of the nitrogen compounds.

In addition to the undesirable nitrogen compounds, hydrocarbon oils may also contain small quantities of peroxygenated hydrocarbons which are instrumental in catalyzing the decomposition of products derived from the oils.

Various methods have been proposed'for the removal of these deleterious compounds from hydrocarbon oils, but none of these has proved to be completely satisfactory. In one proposed method, as much as percent or more of the hydrocarbon is lost during such treatment and, moreover, the treatment produces gaseous decomposition products which are undesirable. Another method removes appreciable quantities of other reactive and non-detrimenta1 constituents of the oil.

In the case of'crankcase lubricating oils these deleterious constituents apparently render the oil highly corrosive and thermally unstable, and therefore, it has been proposed to reduce the corrosiveness and increase the stability of the oil by adding thereto certain inhibiting compositions. It has now been found that the susceptibility of the oil to these anti-corrosion and stabilizing additives is substantially enhanced when the oil is first reacted with a reagent which selectively removes certain of the deleterious constituents initially present in the oil.

It is, therefore, an object of this invention to provide a process for improving nitrogen-containing heavy hydrocarbons. Another object is to provide a process of treating nitrogen-containing hydrocarbons derived from mineral sources. A further object of this invention is to provide improved heavy hydrocarbons derived from mineral sources. Another object is to provide a reaction whereby detrimental constituents are removed by precipitation from a hydrocarbon oil. A particular object-of this in vention is to provide a process for treating heavy liquid hydrocarbon oils containing nitrogen for use in the manufacture of gasoline by the catalytic cracking process.

still further object of this invention is to provide imcontaining oil.

2,862,879 Patented Dec. 2, 1958 proved heavy liquid hydrocarbon oils which yield finished products of great usefulness and stability. Another par ticular object is to provide a crankcase lubricating oil having greatly increased thermal stability.

The above and other objects of this invention will become apparent from the following specification and attached drawings in which: 1

Figure l is a schematic representation of an embodiment of this invention as applied to crude petroleum;

Figure 2 is an embodiment of this invention applied to the primary distillation products of a crude liquid hydrocarbon oil, and;

Figure 3 is a further embodiment of this invention applied to more highly refined liquid hydrocarbon oils.

The objects of this invention are accomplished by a process which comprises reacting a nitrogen-containing heavy hydrocarbon oil having a gravity heavier than 32 API with an ester of a metaboric acid, whereby a pre cipitate is formed in the hydrocarbon oil, and separating the precipitate and the hydrocarbon oil. This precipitate apparently results from reaction of the metabor ic acid with certain undesirable nitrogen-containing constituents of the hydrocarbon.

The nitrogen-containing heavy hydrocarbon oil used in the process of this invention is aliquid derived from mineral sources, and has a gravity rating heavier than 32 API. Thus, this liquid hydrocarbon is derived from petroleum, coal, shale, tar sands, etc., and includescrudes, reduced crudes, cracker charge stocks, lubricating oil distillates, residual stocks, cylinder stocks, steam-refined stocks, paraffin extracts, asphalt extracts, and the various hydrocarbon products derived from these.

In general, however, the heavy nitrogen-containing hydrocarbon oils reacted in the process, in addition to a gravity heavier than 32 API, have a viscosity of at least about 42 seconds Saybolt Universal at F.

The novel product which results from the reaction of a nitrogen-containing heavy hydrocarbon oil and an ester of a metaboric acid not only possess the beneficial attributes resulting from a lowered nitrogen content, i. e., reduced antagonism to cracking catalysts, but also has a greatly increased thermal stability and resistance to oxidative deterioration. This increase in stability is most pronounced when an excess of rn'etaborate ester is reacted with the oil. Thus, a preferred embodiment of this invention comprises reacting a nitrogen-containing heavy hydrocarbon oil having an API gravity heavier than 32 with an ester of a metaboric acid, whereby a precipitate is formed in the oil, the ester being present in the reaction in excess of the amount necessary to form the precipitate, and separating the precipitate and they ester- Another preferred embodiment is the novel ester-containing oil which is the product of the reaction just described.

Another embodiment of the instant invention comprises reacting a nitrogen-containing crankcase lubricating oil with an ester of a metaboric acid, whereby a precipitate is formed in the oil, the ester being present in excess of the amount required to form the precipitate, separating the oil and the precipitate, removing the excess ester from the oil, and then adding to the oil from about'0.001 to about 1.0 weight percent of boron as an ester of a boron acid. A further embodiment is the novel boron-containing lubricating oil prepared by the process just described. Boron can be added'to the oil which has been reacted with an ester of a rnetaboric acid in the form of a soluble, hydrolytically stable organic ester of a boron-containing acid. Thus, esters of orthoboric acid (H BO metaboric acid (HBO ),pyroboric acid (H B O borinic acid (H BO), boronic acid 3 (H BO as well as biborates and other boron-containing esters are conveniently added to the oil. The resulting lubricating oil which has been reacted with an ester of a metaboric acid and which contains boron as an ester of a boron acid has a greatly improved thermal stability and exhibits greatly reduced corrosion tendencies.

To illustrate the adaptation of the process of this invention to typical refinery operations, reference is made to the accompanying schematic drawings. As shown in Figure l a petroleum crude is conducted from a storage tank 10, as shown at line 11, to a treating tank 12 where the oil is reacted with an ester of a metaboric acid in an appropriate solvent. The metaboric acid solution enters the tank 12 via line 13. The reaction mixture in the tank 12 is agitated and heated to promote formation of a precipitate which is allowed to settle and is removed from the tank through line 14. The clear oil is then conducted by line 15 to a primary steam distillation ap-' paratus 16. Steam distillation separates the crude into various components including the light distillates 17, catalytic cracker charge stocks 1S, and undistilled residuum, i. e., reduced crude 19. These various components are 'then subjected to further refinery or blending operations.

Figure 2 is illustrative of an embodiment of this invention wherein the crude petroleum, which enters a distilla- -tion unit 21 via line 20, is first subjected to a primary steam distillation to yield as effiuents the light distillates 22, catalytic cracker charge stocks 23, and a reduced crude oil 24. The catalytic cracker charge stocks are conducted via line 23 to a reactor 25 where they are reacted with an ester of a metaboric acid which is indicated entering the reactor by line 29. The reaction is conducted with heat and agitation and a precipitate forms in the stock. This precipitate is allowed to settle and is removed from the reactor 25 by line 30. The thus treated catalytic cracker charge stock is then removed from the reactor 25 to further refinery processing as illustrated by line 27. The reduced crude is likewise reacted with a metaboric ester, and is conducted via line 24 from the distillation unit 21 to a suitable treating tank 26 where it is reacted with heat and agitation with an ester of a metaboric acid which enters the tank 26 through line 31. As a result of the reaction, a precipitate forms in the oil which, on settling, is removed from the tank 26 by line 32. The reduced crude which has been reacted with a metaboric ester leaves the tank 26 by line 28 to further refinery processing.

When it is desired that only particular fractions of semirefined hydrocarbon oils be subjected to reaction with a metaborate ester, the reaction may be conducted at an advanced stage in the refining process, as illustrated in Figure 3 of the accompanying drawings. In this embodiment of the invention, a reduced paratfinic type crude 15 shown at line 33 entering a second stage distillation appav ratus 34 where it is separated at reduced pressure into volatile fractions which leave the still 34 by line 36. The volatile fractions are conducted via line 35 to further intermediate refinery processes, in this case solvent extraction 37 from which the oil is conducted through line 39 to a solvent dewaxing unit 38 and then via lines 40, to a final distillation tower 41 where it is separated into its ultimate components. These components include gas oil which leaves the still 41 via line 42, a non-viscous neutral oil which leaves the still 41 via line 43, and a lubricating oil fraction which is removed via line 44. The lubricating oil fraction is conducted by line 44 to a tank 45 where it is reacted with an ester of metaboric acid, which enters the tanks 45 via line 62. The reaction is conducted at an elevated temperature while the oil is agitated.

After a precipitate is formed, the oil is conducted from the tank 45 by line 46 to a clay filtration unit 47 where the oil is freed of the precipitate. The steam refined stock is conducted by line 36, from the distillation apparatus 34 to a solvent extraction unit 48 and then, via line 49, to a clay filtration unit 50. After clay filtration, the steam refined stock is conducted by line 51 to a solvent dewaxing unit 52. After wax is removed the oil' is conducted, via line 53, to a treating tank 54 where it is reacted with an ester of a metaboric acid at high temperature with constant agitation. The metaborate ester enters the tank 54 through line 61. After a precipitate has formed, the oil is conducted from the tank 54 by line 55, to a clay filtration unit 56. After clay filtration, which removes the precipitate, the steam refined stock, which may now be referred to as a bright stock oil, is conducted, in the proper proportions by line 57 to a blending tank 59 where it is mixed with the lubricating oil fraction from the clay filtration 47, which enters the blending tank 59 by line 53. To produce a completely finished lubricating oil, various additives, which are introduced into the tank 59 via line 60, are blended with the bright stock and lubricating oil fractions.

As pointed out, esters of metaboric acids are used as the reagents in this invention. These esters must meet two requirements: (1) They must be soluble in the hydrocarbon being treated and (2) they must be resistant to oxidative deterioration. As to the first requirement, the ester functions when dissolved in the hydrocarbon being treated. Preferably, the ester of a metaboric acid used should have sufiicient solubility in the hydrocarbon being treated, such that on bringing the metaborate ester in contact with the hydrocarbon, a solution of the former in the latter occurs almost immediately. However, in the instant process esters of a metaboric acid which dissolve in the hydrocarbon more slowly or less completely can be used successfully. Physical agitation, such as stirring, is helpful when using these less-soluble esters. In most cases, that portion of the ester dissolved in the hydrocarbon is consumed in effecting improvements therein. This enables additional treating agent to pass into solution and exert its function. The reagents used should be soluble in the liquid hydrocarbon being treated to the extent that a solution containing at least 0.0004 percent by weight of boron can be achieved.

The second requirement of the metaborate ester reagents is that they be resistant to oxidative deterioration. Resistance to oxidative deterioration can be readily measured by subjecting the reagents to Test Procedure D-525 of the American Society of Testing Materials. This procedure measures the extent to which the test material is degraded by oxygen when the material is placed in a test bomb maintained under oxygen pressure of p. s. i. g. at a temperature of 100 C. In short, the esters used in the process of this invention must not be deteriorated when in contact with air and, for this reason, these reagents are nitrogen free. An attempt to employ an oxygen-sensitive ester of a metaboric acid in the process of this invention would be futile because the treating agent would be decomposed or otherwise chemically modified to the extent that it could not exert its beneficial function.

There are four metaboric acids which form esters which are suitable in the practice of this invention. These acids have the empirical formulas HOBO, HOBS, HSBO and HSBS. Thus, esters of these metaboric acids, which esters meet the above requirements for use as reagents pursuant to this invention, have the empirical formula RYBZ wherein R is selected from the group consisting of alkyl, aralkyl, cycloalkyl, aryl, alkaryl, alkoxyalkyl, poly(alkoxy)-alkyl, and aryloxyalkyl; and Y and Z are selected from the group consisting of oxygen and sulfur. It is preferable that the R groups contain up to about 18 carbon atoms, although in most cases, R groups containing up to about 8 carbon atoms give the best results and, for this reason, are particularly preferred. Under usual conditions-4. e., normal temperatures and pressures-the above esters of metaboric acids exist as trimers having the formula wherein R, Y and Z are as designated above.

Preferred metaborate reagents used in this invention are esters of metaboric acid. In other words, Y and Z in the above formula are both, oxygen in these preferred compounds. Isopropyl metaborate is an excellent example. These compounds are preferred as they are read ily prepared from inexpensive starting materials.

The metaborate ester reagents of this invention can be mixed with esters of other boric acids, such as ortho borate esters. Advantages of using such mixtures are .that they are easily prepared and that orthoborate esters are good drying agents. Thus, these easily-prepared mixtures, when-contactedwith liquid hydrocarbons as defined above which contain small amounts of water, possess the feature that the orthoborate ester portion of the mixture is consumed in drying thehydrocarbon thereby enabling .the metaborate ester to exert its beneficial function. These advantages are somewhat offset by the fact that esters of boric acids other than esters of metaboric acids do not exert the beneficial function exhibited by the metaboric esters themselves. This means that only a portion of the mixture is'capable of bringing about the improvements in the hydrocarbons. Thus, it is desirable that when a :mixture of esters of boric acidsisused, at least about percent by weight of the mixture is an ester of a metaboric acid as defined above. Preferably, these mixtures contain a major proportion of an ester of a metaboric acid. By using such mixtures, the total amount of reagent needed is reduced to a satisfactorily small amount. Under no circumstances can the process of this invention becarried outwith a mixture of boric acid esters which does not contain an ester of a metaboric acid.

The process of this invention. is simple and economical. The metaborate reagent is readily handled and is free from obnoxious or dangerous characteristics. For example, most of the treating agents of this invention are normally solids having low vapor pressures. They are relatively non-toxic and can be used without the necessity of stringent safety precautions. No gas is used or formed during the process.

Not only is the process of this invention relatively simple, economical and non-hazardous, but the achieved results are substantial. The nature and importance of the improvements brought about by this invention are considered hereinafter.

When conducting the processof this invention, a precipitate is formed at slightly elevated temperatures from reaction between the metaborate reagent and the hydrocarbon oil. Because the hydrocarbon oil has a relatively high specific gravity and may have a relatively high viscosity, it is desirable to assist the formation, coalescence and separation of the precipitate. Formation of the precipitate is facilitated by agitation to' disperse the metaborate through the oil and by the application of heat to initiate the reaction between the oil and ester. Coalescence is achieved by the use of agitation and the application of heat. To separate the coalesced precipitate from the hydrocarbon, various procedures are available. For example, when the hydrocarbon has a viscosity of heavy gas oil, it can be maintained in the quiescent state for a period of time suificient to enable the precipitate to settle to the bottom of the treating vessel. This precipitate can then be separated from this type of hydrocarbon by decantation, filtration, centrifugation and like procedures. On the other hand, when the hydrocarbon has a viscosity greater than thatof a heavy gas oil, it is preferabletoeni,- ploy. asettling aid, such as activated clay or thelik'je, to facilitate removal of the precipitate. The viscous hydro} carbon can be agitated preferably at elevated temperature and then subjected to filtration or centrifugation. Ar other method of achieving separation of the precipitate from the more viscous hydrocarbons is dilution of the hydrocarbon with a non-viscous hydrocarbonto form a less viscous system, separating the precipitate from the system by any of theabovemethods and then separating the diluent from the hydrocarbon by distillation, or like procedures. Electrostatic precipitation or other methodsof facilitatingthis separation can alsobe employed.

A highly important feature of the present process is that there i sonly a-negligible loss in hydrocarbon volume sustained. This results from the selectivity of the reaction. Thus, unlike various conventional refinery processes, the process ofthis invention brings aboutsubstang tial improvements in the hydrocarbon without sacrificing significant amountsof the hydrocarbon in the course of the treatment. Generally speaking, the losses in hydro; carbon volume sustained when practicing the present process are less than aboutone-percent, In the case of some crude oils which contain an unusually high concentration of nitrogen, the losses sustained. may be somewhat higher, although even such losses are insignificant. The importance to the petroleum refiner of this feature of the invention will be immediately apparent.

Anyexcess quantities of. the metaborate reagent canbe left in the liquid hydrocarbon or it can be removed therefrom.

Ordinarily, in the practice ofthe invention the metaborate reagent is added to: and blended; with the hydrocarbon, although the reverse, procedure can be used. The reaction takes place at. a. temperature less. than the boiling temperature ofthe hydrocarbon at the prevailing pressure. Thus, the temperaturemay range from about 70 F. to about.750 F., depending in part upon the nature of the metaborate reagent used and the hydrocarbon being treated. The preferred temperature range is from about 70 F. to about 500 F. To insure that the reagent comes in intimate contact with the body of the hydrocarbon, physical agitation, such as stirring, shaking or the like, is used. The precipitate which forms in the hydrocarbon is then separated by proceduresas set forth above.

The methods of carrying out this invention will be still further apparent from thefollowing specific examples in which all parts and percentages are by weight, unless otherwise specified. Where the results of chemical analyses for nitrogen and boron are presented, it will be understood (1) that weight percent of nitrogen refers to the content of complex nitrogenous compounds present in the hydrocarbon expressed in terms of elemental nitrogen and (2) that weight percent of boron refers to boron content expressed in terms of elemental boron, although the boron is actually present in the form of boron compounds-chiefly metaborate esters.

EXAMPLE I Two thousand parts of a nitrogen-containing gas oil having a boiling range of 400 F. to 510 F. and an API gravity of 3l.9 is reacted with 4 parts of benzyl metaborate. The mixture is heated to 300 F. with agitation, and after the metaborate ester is thoroughly blended with the oil, the mixture is allowed to stand without agitation until the precipitate "settles out. The oil is then separated from the precipitate bydecantation, and a sample is analyzed for nitrogen. The nitrogen content of the treated oil is foundto be considerably below that of the untreated oil.

This example shows that the treating agents of this invention can be used without recourse to solvent. However, it is particularly advantageous to dissolve an appropriate quantity of metaborate reagent in a suitable solvent, such as toluene, or other organic liquids in which these reagents donot form precipitates. By using the metaborate reagents in a preformed solution, the

blending procedures used in the instant process are sim- EXAMPLE 11 Twenty-five parts of. a 30% solution of n-butyl metaborate in heptane is reacted with 600 parts of a reduced crude oil having an initial boiling point of 515 F., a 50% boiling'point of 940 F., a gravity heavier than 30 API, and which contains 0.78% nitrogen. The mixture is agitated while the temperature is raised to 500 F. The oil is subsequently cooled, separated from the precipitate which forms on addition of the metaborate solution, and an aliquot analyzed for nitrogen. The nitrogen content of this treated'oil is found to be substantially below the original nitrogen content of the untreated oil.

EXAMPLE IH Example II is repeated except that parts of tribenzyl orthoborate is added to 1000 parts of the oil in lieu of the n-butyl'metaborate solution. No precipitate is formed when the mixture is heated to 500 F. The nitrogen content of this oil is found to be unchanged after treatment with the orthoborate.

EXAMPLE IV 'theoil. No precipitate forms in the oil. A sample of the thus treated oil is analyzed for nitrogen and the nitrogen content is found to be substantially unchanged from the original 0.49%.

EXAMPLE V Five parts of triisopropyl orthoborate is added with agitation to 300 parts of the oil described in Example I and the mixture is heated to 350 F. but no precipitate forms. Analysis of this oil for nitrogen indicates that the nitrogen content thereof is substantially unaltered from the nitrogen content of the untreated oil.

That it is essential to employ an ester of a metaboric acid is established by Examples III through V. It will be seen that when pure orthoborate esters are used, the nitrogen content of the oil treated is unchangd.

EXAMPLE VI Fifteen parts of a 40% soution of isopropyl metaborate in tolene is reacted with 1000 parts of a nitrogen-containing gas oil having a boiling range of from 400 to 510 F. and an API gravity of 319. This oil is derived by distillation from a California crude with an initial boiling point of 149 F., a 29% boiling point of 482 F. and a gravity of 23.1 API. The'metaborate solution is thoroughly blended with the oil'and the mixture is heated to 150 F. The oil is then allowed to stand until the precipitate settles to the bottom of the reactor. After separation of the precipitate the oil is treated with water and a precipitate again forms in the oil and is allowed to settle. A sample of the precipitate-free oil is found on analysis to be free of boron and to have a reduced nitrogen content.

EXAMPLE VII Ten parts of cyclohexyl metaborate is added with agitation to 50,000 parts of a gas oil at 400 F. This oil has an initial boiling point of approximately 410 F. and a gravity of 32 API. This oil is derived by distillation from a Texas crude having an initial boiling point of 171 F. and a gravity of 300 API. After removal of the precipitate that forms on addition of the cyclohexyl metaborate the oil is treated with water to remove the excess cyclohexyl metaborate. The treated oil has a reduced nitrogen content.

Examples VI and VII illustrate the process of this invention applied to gas oils which are intended for use as charge stocks in the manufacture of gasoline by the catalytic cracking process. When the oil is to be charged to a catalytic cracker it is desirable to remove any metaborate therefrom which is in excess of the amount necessary to form a precipitate in the oil, so that the boroncontaining reagents are not present during the cracking operation. This may conveniently be done by hydrolyzing any remaining metaborate with water. However, since some of the metaborate ester treating agents of this invention are water insensitive recourse to other methods of removing any excess of treating agent may be necessary. Thus, in the case of a water stable metaborate, recourse may be had to distillation or decomposition of the metaborate with strong acids or bases. By removing the boron treating agent from the hydrocarbon, the effective life of the cracking catalyst is extended. Thus, an additional embodiment of this invention is the process which comprises contacting a nitrogen-containing heavy hydrocarbon oil having an API gravity heavier than 32, with an ester of a metaboric acid, whereby a precipitate is formed in said hydrocarbon, the metaborate ester being present in the hydrocarbon in excess of the amount required to form the precipitate; separating the precipitate and the hydrocarbon; and separatingfrom the hydrocarbon the excess amount of metaborate ester.

EXAMPLE VIII To 1,000 parts of a nitrogen-containing California neutral oil having a viscosity of 381.6 seconds Saybolt Universal at F., a viscosity index of 4, a gravity of about 26 API and a flash point of 345 F. is added 5 parts of benzyl metaborate, and the reaction mixture is .heated to F. with'agitation. The oil is separated from the precipitate by filtration. The clear oil has substantially less nitrogen after the reaction.

EXAMPLE IX Sixteen hundred parts of a nitrogen-containing Mid- Continent neutral oil having a viscosity of 524.8 seconds Saybolt Universal at 100 F., a viscosity index of 51, a

gravity heavier than 30 API, and a fiash point of 370 F. is reacted with 2 parts of n-butyl metaborate. The agitation is discontinued, but the temperature is maintained at 200 F. until the precipitate coalesces sufficiently to facilitate filtration. The oil has a lower nitrogen content after the reaction.

EXAMPLE X EXAMPLE XI Twenty parts of methyl metaborate dissolved in 50 parts of dibutyl phthalate is reacted with 1,200 parts of a nitrogen-containing Pennsylvania bright stock having a viscosity of 2520 seconds Saybolt Universal at 100 F., a viscosity index of 99, and a gravity heavier than 26 API. The methyl metaborate solution is thoroughly blended with the oil at250 F. and the precipitate formed is removed by conventional clay filtration. The filtered oil has a greatly reduced nitrogen content.

a 9 EXAMPLE x11 One hundred parts of a nitrogen-containing acid treated asphalt base light lubricating. oil distillate having an API gravity of 23.7, a viscosity of 317 seconds Saybolt Universal at 100 F. and a viscosity index of 27 is reacted with 4 parts of phenyl metaborate according to the procedure outlined in Example XI. Analysis of ,the oil before and after the reaction indicates that the nitrogen content thereof is greatly reduced by the reaction.

EXAMPLE XIII EXAMPLE XIV Fifteen parts of O-octyl thiometaborate is reacted at 200 F. with agitation to .450 parts of a parafi inic nitrogencontaining steam refined stock having a viscosity of 153 seconds Saybolt Universal-at 210 F., a viscosity index of 99, and an API gravity. heavier than.25. After the O-octyl thiometaborate is completely dispersed through the oil and a precipitate has formed, the mixture is subjected to clay filtration. The filtered oil has a much re-v duced nitrogen content.

EXAMPLE XV Ten parts of S-phenyl thiometaborate is reacted at 200 F. with 300 parts of a dewaxed neutral oil having a viscosity of 195 seconds Saybolt Universal at 100 F., a viscosity index of 100 and an API gravity of 30.4". The precipitate is separated by filtration, and the resulting oil has a greatly lowered nitrogen content.

EXAMPLE XVI Five parts of octadecyl metaborate is reacted with agitation at 150 F. with 125 parts of, a Mid-Continent solvent refined stock which contains nitrogen and has a viscosity, of 120.5 seconds SayboltUniversal at 210 F., a viscosity index of 97, and an API gravity heavier than 30.

EXAMPLE XVII A mixture of benzyl bora tes containing benzyl metaborate was prepared by digesting boric oxide with 55% of the theoretical amount of benzyl alcohol necessary to make tribenzyl orthoborate. The temperature of this digestion was 200 C. The resulting mixture of benzyl borates contained approximately 70% byweight of benzyl metaborate. This mixture was dissolved in half its Weight of dibutyl phthalate.

One hundred parts of this mixture of benzyl borates'in dibutyl phthalate is reacted with 7,000 parts ofa Mid- Continent solvent refined neutral oil having a viscosity of 215 seconds Saybolt Universal at 100 F., a viscosity index of 100, and a gravity heavier than 28 API. The reaction mass is agitated and the temperature is raised to 230 F. to encourage formation of the precipitate. This mixture is then subjected to clay filtration and the resulting clear oil is analyzed for nitrogen and found to contain substantially less nitrogen than the untreated oil.

EXAMPLE XVIII Ten parts of the mixture of benzyl metaborate and tribenzyl orthoborate prepared as described in Example XVII is reacted with 250 parts of a nitrogen-containing furfural extracted residual stock at 475 F. This oil has a viscosity of 2524 seconds Saybolt Universal at 100 R, an API gravity of 26.5 and a viscosity index of 95.5.

t 10 Vigorous agitationds required :toassure complete f rniation of the precipitate. The reactionrnass is then cooled and. diluted with,200,- parts of petroleum ether, filtered, and subjectedto atmospheric distillation toremove the ether. The resultingoil has a much lower nitrogen content than the orig inalunreacted oil.

EXAMPLE" XIX Three hundred eighteen parts of a toluene solution of isopropyl rnetaboratecontaining 13.2 parts of boronwere reacted with 32,900 parts of a commercially available light neutral lubricating oil. at 50 C. The. oil had a gravity of 31 .l API, a.viscosit y of 125.4 seconds Saybolt Universal at F., and contained 0.0029% basic nitrogen before reactionwith the metaborate, The reaction mixture was stirred for. 11 hours at 50? C. and then the gelatinous precipitate was allowed to settle at room temperatureffor 3'1v hours. The precipitate was removed from the oil by filtration. Analysis of the oil after filtration showed that the basic nitrogen content wasonly 0.001 l,%, andthatsubstantially all the boron remained in theoil,

EXAMPLE XX oilshowedthat only,0.0002% basic nitrogen was present.

EXAMPLE XXI Example XIXwas repeated' and 1645 of the filtered oil were diluted with an equal ,volume of petroleum ether andwashed twice with 700 parts of water. The oil Was then separated fromth'e water, driedfor one hour over drierite and the ether was removed by distillation. When analyzed, the. resulting oil was foundto be boron free. Triamyl orthoborate wasth'en added to the oil in amount sufiicient to give a composition containing 0.05% by weight of boron. The resulting oil had a greatly increased thermal stability.

Example XXI'is illustrative of that embodiment of the invention wherein an oil is first reacted with an ester of ametaboric acid, freed from the precipitate which forms during the reaction, freed from the excess metaborate, and thentreated with an ester of a boron acid. Other esters of boron acids can be added to an oil which has been reacted with. an ester of metaboric acid in the practice of this invention. Some examples of these boron esters are: isopropyl metaborate, benzyl metaborate, tribenzyl orthoborate, hexylene glycol biborate, 2-methyl- 2,4-pentylene ortho borate, bis(2-methyl-2,4-pentylene) pyroborate, triisopropyl orthoborate, tert-butyl boronate, hexyl borinate, bis(l,3-propylene) pyroborate, tri-n-butyl orthoborate, and esters of the sulfur analogues of the various boron acids.

EXAMPLE XXII Example XIX is repeated and 88 parts of the filtered oil which has been reacted with isopropyl metaborate are enter into the formation of the precipitate. It has been found that the nitrogen content of the hydrocarbon is re:

reaction.

performance characteristics.

'duced to an extremely low concentration even where the initial nitrogen content was very high. It has also been found that certain oxygen-containing constituents are removed from the hydrocarbon during the course of the Such oxygen-containing constituents are exemplified by peroxides and hydroperoxides.

Finished lubricating oils prepared from non-finished hydrocarbon stocks treated pursuant to this invention are the use of finished lubricants derived from hydrocarbons treated in accordance with this invention as crankcase lubricants contributes substantial improvements in engine Moreover, such finished lubricants exhibit reduced bearing-corrosion tendencies.

The advent of the modern high-compression automobile engine led to the use of lubricating oils which contain a high proportion of lower boiling distillate oils, even though these oils are inferior in their lubricating qualities. This was necessitated by the fact that these lower boiling oils are more resistant to oxidative decomposition than are the higher boiling oils. Since, when treated by the process of this invention, the higher boiling oils exhibit a far superior resistance to oxidative decomposition, it

'has now become possible to again blend satisfactory lubricating oils which contain a high proportion of heavier boiling oils and which are thus superior lubricants.

Hydrocarbon oils treated in accordance with this invention possess greater stability as compared with the corresponding untreated oils. This results from the removal of peroxides and hydroperoxides from the oil during treatment. Therefore, the hydrocarbon possesses enhanced resistance against oxidative deterioration. This is surprising because the reagents themselves, particularly the esters of metaboric acid, are not antioxidants.

To demonstrate the superiority of a crankcase lubricating oil which has been reacted with a metaborate ester, comparative tests were run on the oils reacted according to Examples XIX and XX and the identical oils which had not been reacted with isopropyl metaborate. These oils were compared by the Panel Coker test which measures the oxidative stability of a lubricating oil at a hot metal surface. This test is described in the Aeronautical Standards group of the departments of Navy and Air Force Specification MIL-L7808c dated November 2, 1955. The results of the tests are summarized in Table I. These data show that a lubricating oil which has been reacted with a metaborate ester has a greatly reduced coking tendency at elevated temperature when compared to an identical oil which has not been reacted with a metaborate ester. Thus, the oil which has been reacted with a metaborate ester has a greatly enhanced thermal stability and a superior resistance to oxidative deteriora- The oil which is described in Example XIX was also subjected to a test which measures the lubricity of a lubricant. This test, known as the Four Ball Wear Test, is described in Naval Research Laboratory Report No. 3709, dated September 1950. The results of this test indicate that the oil which had been reacted with a metaborate ester has superior lubricating properties compared to the properties of the identical oil which had not been reacted with a metaborate ester. These are summarized metaborate; .O-phenyl-thiometaborate:

in Table II.

Table II FOUR BALL WEAR TEST Scar Diameter Load Oil Alter Re- Unreacted action with Oil Metaborate Ester the oil which was first reacted with the metaborate ester and freed of the excess has a greater thermal stability than the unreacted oil when both have the same concentration of added boron ester.

Table III PANEL COKER TEST Milligrams of Deposit Oil Unreacted Metaborate Oil Reacted 011 Example XXII 56 42 Nitrogen-containing hydrocarbon oils, when treated by the instant process, can be readily subjected to cracking operations without fear. of poisoning the cracking catalysts. Thus, the instant invention makes available to the petroleum refiner a means of pretreating cracker charge stocks so as to remove therefrom the deleterious nitrogen compounds initially present. Once this removal has been effected the refiner has his choice as to the type of cracking process to be used in further processing the cracker charge stocks. Irrespective of the type of cracking operation selected, the pre-treatment of the charge stock in accordance with this invention greatly extends the life of the cracking catalyst and greatly simplifies the cracking procedure. Moreover, the products derived from this cracking operation are pure and contain substantially reduced quantities of undesirable constituents as compared with the products obtained by cracking hydrocarbons which have not been treated pursuant to this invention.

Typical reagents of this invention having the formula include O-methyl thiometaborate; O-ethyl thiometaborate; O-n-propyl thiometaborate; O-isopropyl thiometaborate; the various O-butyl thiometaborates; O-amyl thiometaborates; O-hexyl thiometaborates; O-heptyl thiometaborates; O-octyl thiometaborates; O-nonyl thiometaborates; O-decyl thiometaborates; O-undecyl thiometaborates; O-didecyl thiometaborates; O-octadecyl thiometaborates; O-cyclohexyl thiometaborate; O-methylcyclohexyl thio- O-o-, 111-, and p-tolyl thiometaborates; O-xylyl thiometaborates; O-ben- 13 'zyl thiometaborate; Q-(fi-ethoxyethyl) thiometaborate; O-( (fi-ethoxyethoxy) ethyl thioinetaborate; O- (fiflahenoxyethyl) thiometaborate; and the like. i

Reagents having the formula R i o include such compounds as S-methyl metaborate; S-ethyl metab'orate; S-n-propyl metaborate; S-isopropyl metaborate the various S-butyl metaborates; S-amyl metaborates; S-hexyl metaborates'; S-heptyl metaborates; S-octyl metaborates; S-nonyl metaborates; S-decyl metaborates; S-undecyl metaborates; S-dodecyl metaborates; S-octadecyl metaboratet S-cyclohexyl metaborate; S-methylcyclohexyl metaborate; S-phenyl metaborat e; S-o- ,m-, and ptolyl metaborates; S-xylyl metaborates; S-benzylmetaborate; S- (,8-ethoxyethyl) metaborate; S-(B-(B-ethoxyethoxy) ethyl) metaborate; S-(B-phenoxyethyl) metaborate; and the like. 7 w

Those reagents having the formula include S-methyl thiometaborate; S-ethyl thiornetaborate; S- n-propyl thiometaborate; S-isopropyl thiometaborate; thevarious S-butyl thiometaboratesfSamyl thiometaborates; S-hexyl thiornetaborates; S-heptylIthiometaborates; s octyl thiornetaborates; S-nonyl thiometaborates;.S-idecyl thiometaborates; S-undecyl thiometaborates; Sdodecyl thiometaborates; S-octadecyl thiometaborate; S-cyclohexyl thiometaborate; S-methylcyclohexyl thiometaborate; S-phenyl thiometaborate; S-o-, m-, and p-tolyl'thiometaborates; S-xylyl thiometabo-rates; S-benZyl-thiometaborates; S-(flethoxyethyl) thiometaborate; S-(B-(B-ethoxyethoxy) ethyl) thiometaborate; S- ,B-phenoxyethyl) thiometaborate; and the like.

Preferred reagents include such compounds as methyl Inetaborate; ethyl metaborate; n-propyl metaborate; isopropy metaborate; the various butyl metaborates; amyl metaborates; hexyl metaborates; heptyl metaborates; octyl metaborates; nonyl metaborates; decyl metaborates; undecyl metaborates; dodecyl metaborates; octadecyl metaborates; cyclohexyl metaborate; methyL-cyclohexyl metaborate; phenyl metaborates; 0-, m-, and p-tolyl metaborates; xylyl metaborates; benzyl metaborate; [ft-ethoxyethyl metabo-rate; fi-(fi-ethoxyethoxwethyl metaborate; B-phenoxyethyl metaborate; and the like. Of these compounds, those in which the R groups contain up to about 8 carbon atoms are particularly preferred.

To prepare the above metaborate ester reagents, the following reactions are used:

O-substituted thiometaborates (l) 3HSBS +B(QR) (ROBS) +B(SH) S-substituted metaborates Q-substituted metaborates 3HOBO+3ROH (RQBO)3+ 3H;O

Reactions 1 and 4 are preferably carried out inrefluiring carbon disulfide. Reactions2, 3, 5 and 6' arefcoiiv n e y car e u in ef xin o ne; Rea tion d es require a Q i h 3 0n empera ure is from 100 to 150? C h sfq o sp fi ampl s. lust a e he p p ration of treating agents ofthis invention. In; thesev ex; es a parts and per eut e are v 'e h 7 EXAMPLE XXIII ,In a reaction vesselequipped with heating and. condensing means'were placled g 130.5. parts of orthoboric acid and 433 parts of toluene: This mixture wasirefiuxed at about 110C. whereby 3 9Iparts of water wasnrern ove d from the system as atoluene a zeotrope. To the resultant slurry was slowly added 132 partsof isopropanol over a period of 4.5 hours. The mixture was then refluxed at about 110 C. so that 45.5 partsof waterwisopropanol mixture wasrerrioved as a toluene azeotrope. The so; lution remainingv in thereaction vessel was subjected to chemical analysis which showed the presence of 3.82 percent ofv boron. Infrared analysisshowed this. solution to contain a maximum of 4 percent.oftriisopropyl orthoborate with theremainder being isopropyl metaborate. The toluene was then, removed from this solution by distillation and isopropyl metaboratewas frecoverecl by recrystallization from mixture ofbenzen eandpetroleumetherQ i The isopropyl metaborate.so recoveredi was a white solid having a melting pointio f. 50 C. Chemicalanalysisshowed this solid to containl2 .5l percent of boron and to have a molecularweight of 253, which corresponded tothe theoretical values of 12.6 percentof boron andfa molecular. weight er 258. 0'

EXAMPLE xxrv To 86 parts of toluene were added 25 parts of cyclohexanol. and 15.5 parts of orthoboric acid. Thi s rnixture was heated to about 110 C. until 9 parts of water was removed from the reaction system as a toluene azeotrope. Reaction was completed in 30 minutes toluene was removed by distillationfrom the clear solution remaining in the reaction vessel, leaving a white, flufiy productcyclohexyl metaboratemelting at approximately 140 C.

EXAMPLE XXV A mixture of 80 parts of orthoboric acid and 224 parts of benzyl alcohol was heated to 230 C. for one hour. 49 parts of water was evolved and removed from the system. The resulting solution was dissolved in an equal volume of benzene and then 10 times this volume of petroleum ether was added. A heavy liquid phase consisting of benzyl metaborate separated. Foundv 8.0 5

percent. of boron, 5.29 percent of'hydrogen, 62.;5 .per-

cent of carbon, molecular weight 391. Theoryforbenzyl metaborate-8.1O percent boron, 5.27 percent of-hydro gen, 62.9 percent of carbon, molecular weight 402,-

EXAMPLE XXVI 22.6 parts of p-ethoxy ethanol, 15.5 parts oforthoboric acid and 86 parts of toluene were heated'at about C. for 40 minutes. 10 parts of Water-Wasevo1ved and removed from the system as'a toluene azeotrope.

7 l in admixture. Moreover, the treating agents can be mixed with esters of other acids of boron, such as orthoboric acid, mesoboric acid, dihydrodiboric acid, hexahydrotetraboric acid, hydrotetraboric acid, hexahydrooctob'oric acid, dihydrooctoboric acid, dihydrodecaboric acid, dihydrododecaboric acid, etc. r 1

Solvents which can be used in conjunction with the above metaborate esters include pure parafiin hydrocarbons, such as pentane, mdecane, etc.; aromatic hydrocarbons, such as benzene, toluene, xylene, mesitylene, etc.; cyclohexane; cyclohexene; halogenated hydrocarbons, such as chloroform, carbon tetrachloride, methylene dichloride, amyl chloride, bromobenzene, etc.; esters, such as ethyl acetate, amyl acetate, butyl phthalate, octyl sebacate, etc.; ethers; ketones, such as acetone, methylethyl ketone, etc.; and other organic solvents which are inert to the metaborate reagents.

In carrying out the process of this invention the ratio of metaborate ester to hydrocarbon being reacted varies depending upon the nature of the hydrocarbon used. Thus, with relatively pure hydrocarbons, relatively small amounts of metaborate esters are used. When the hydrocarbon being reacted contains a large amount of impurities, a correspondingly greater amount of metaborate is used. Generally speaking, the weight ratio of hydrocarbon oil to metaborate ester in the reaction ranges from about 10,000:1 to about 25:1.

The temperature at which the process of this invention is conducted is dependent upon the particular hydrocarbon oil being treated. Applicable temperatures range upward from the point at which the precipitate forms in the hydrocarbon. The high temperature'limit dependson the stability of the particular metaborate ester used as a reagent and the boiling point of the hydrocarbon. The process of this invention should always be carried out at a temperature below the initial boiling point of the hydrocarbon oil being treated at the prevailing pressure. Thus, the temperature may range from about 70 F. to about 750 F. Preferred temperatures are in the range of about 90 F. to about 500 E.

- The reaction between a heavy nitrogen-containing hydrocarbon oil and a metaborate ester can be carried out at pressures higher than atmospheric when this method is conveniently incorporated into refining operation. When conducted at higher pressures, the reaction can also be conducted at higher temperatures, but always below the initial boiling temperature of the oil at the prevailing pressure.

When the hydrocarbon oil undergoing treatment has a viscosity such that the metaborate ester does not readily also facilitates coalescence and separation of the precipitate which forms when a metaborate ester is added to a liquidhydrocarbon oil.

reagent in excess of that required to react with any water initially present be added to the hydrocarbon oil. In this connection, it is desirable that the reagent be a mixture of esters of metaboric acid and esters of other boron acids as described above. By reacting a liquid hydrocarbon oil in this manner, a greater amount of the valuable metaborate is preserved for reaction with deleterious compounds present in the oil.

As pointed out above, the liquid hydrocarbons which are susceptible to treatment by the process of this inven' tion include heavy nitrogen-containing, liquid hydrocarbon oils which have a gravity heavier than about 32 API and which are derived from mineral sources including petroleum, coal, shale and tar sands. These liquid hydrocarbon oils include crude oils and various intermediate oils derived therefrom, such as reduced crudes, straight run and cracked gas oils, lubricating oil distillates, residual oils, cylinder stocks, steam-refined stocks,

1 parafiin extracts, asphalt extracts and the various hydro- Other aids in the separation of the precipitate and treated hydrocarbon oil may be employed when a'viscous hydrocarbon oil tends to retain the precipitate. Thus, centrifugation, electrostatic precipitation, dilution with a less viscous hydrocarbon, addition of a settling aid, such as activated clay and the application of heat may be employedindividually or in combination to aid in settling and separating the precipitate from the hydrocarbon oil.

As most of the liquid hydrocarbon oils treated by-the process of this invention are initially not anhydrous,'it is desirable to add sufficient metaborate reagent to react not only with the deleterious compounds present, butalso with any water which may bepresent in-the oil As water tends to hydrolyze,'many of the metaborateesters used in the reaction of this invention and thus eliminate them from their intended purposereaction with deleterious nitrogen and oxygen-containing compounds-care,

should be taken that a sufiicient amount of metaborate carbon products derived from these.

These liquid hydrocarbon oils vary in their chemical constituents and physical properties. For example, petroleum cr-udes may vary from very low viscosity to viscosities over 6000 seconds Saybolt Universal at F. Another example of varied properties contained in a single category of hydrocarbon oil is cracker charge stocks, which, generally speaking, have an initial boiling point of from 440 F. to above 525 P. But some hydrocarbon oils, which are referred to as cracker charge stocks, have an initial boiling point as low as F. This same variety in properties is attributable to lubricating oil distillates and other heavy hydrocarbon oils and depends in general on the origin and previous treatment which it has undergone.

Improved finished products obtainable from the hydrocarbons treated by the process of this invention include white oils, saturating oils, emulsifying oils, electrical oils such as transformer oils and switch oils, flotation oils, gasoline, various waxes, lubricating oils including light spindle oils, textile oils, household lubricating oils, compressor oils, metal oils, journal oils, motor oils, steam cylinder oils, compounded oils, valve oils, turbine oils, tempering oils, transmission oils, black oils, grease oils, petrolatum oils, wood preservative oils, boiler fuel oils, road oils, roofing saturants, paint bases, emulsified spray oils, gear grease, axle grease, switch grease, cable grease, cup grease and petroleum jelly.

The above products are manufactured by processes well known to those skilled in the art and may include additives and other compositions in addition to the original liquid hydrocarbon oils. It is unnecessary for the purposes of this invention to go into great detail as to their preparation.

Having fully described the process of this invention in many of its embodiments, the need therefor, the best modes devised for carrying it out and the benefits derived therefrom, it is not intended that this invention be limited except within the spirit and scope of the appended claims.

I claim:

1. A process which comprises reacting a nitrogen-containing heavy hydrocarbon oil having a gravity heavier than about 32 API with an ester of a metaboric acid, whereby a precipitate is formed in said hydrocarbon; and separating said precipitate and said hydrocarbon.

2. The process of claiml in which said ester of a metaboric acid is an ester of metaboric acid.

3. As a new composition of matter a heavy hydrocarbon oil which has been subjected to the process of claim 2. p j

4. A process which comprises reacting a nitrogencontaining heavy hydrocarbon oil having a viscosity at least as high as 42 seconds Saybolt Universal at 100 F., with an ester of a metaboric acid to cause the ester to form a precipitate, the reactants being mixed in propori h that an excess of unreacted ester is present,

17 18 and separating the precipitate from the remainder of the References Cited in the file of this patent mixture. I

5. The process of claim 4 in which after the separation UNITED STATES PATENTS of the precipitate, the excess ester is also separated from 2,675,305 Rogers Apr. 13, 1954 the remainder of the mixture. 5 2,756,181 Hamner July 24, 1956 

1. A PROCESS WHICH COMPRISES REACTING A NITROGEN-CONTAINING HEAVY HYDRICARBON OIL HAVING A GRAVITY HEAVIER THAN ABOUT 32* API WITH AN ESTER OF AA METABORIC ACID, WHEREBY A PRECIPITATE IS FORMED I SAID HYDROCARBON; AND SEPARATING SAID PRECIPTATE AND SAID HDROCARBON. 